[U-Boot-Users] BRGs on ep8248 after updating CLKIN

[U-Boot-Users] BRGs on ep8248 after updating CLKIN

[Alan Bennett]

When I originally supported my ep8248-style board, I had
#define CONFIG_8260_CLKIN	66000000	/* in Hz */

However, I noticed (after far too much time had passed) that my cpu
speed wasn't matching my expectations.  (reported 230 MHz, and
expected 350 MHz).

This was rather easily fixed by changing the CONFIG_8260_CLKIN to 100 MHz:
#define CONFIG_8260_CLKIN	100000000	/* in Hz */

However, my BRGs / SMC1 uart is now broke(baud-rate mismatch).  Does
anyone have experience with this section of u-boot that could help me
out?

My BRG7 is configured by u-boot(1.3+) = 0x00010078 ~ CD = 60 (0x3c).
And there is an apparent baud-rate mismatch and all the output is
garbled now.  (with a scope I measured ~ 25.5 / 26 K, when I'm
expecting 38.4k)

I think I'm missing something in the equation, but I'm not sure where
it is.  If I simply update the CD to be 162 (162*38400*16 = 99,532,800
~ 100 MHz) the serial port is still dead.

Any ideas?

[U-Boot-Users] BRGs on ep8248 after updating CLKIN

[Jerry Van Baren]

Alan Bennett wrote:
> When I originally supported my ep8248-style board, I had
> #define CONFIG_8260_CLKIN	66000000	/* in Hz */
> 
> However, I noticed (after far too much time had passed) that my cpu
> speed wasn't matching my expectations.  (reported 230 MHz, and
> expected 350 MHz).
> 
> This was rather easily fixed by changing the CONFIG_8260_CLKIN to 100 MHz:
> #define CONFIG_8260_CLKIN	100000000	/* in Hz */
> 
> However, my BRGs / SMC1 uart is now broke(baud-rate mismatch).  Does
> anyone have experience with this section of u-boot that could help me
> out?
> 
> My BRG7 is configured by u-boot(1.3+) = 0x00010078 ~ CD = 60 (0x3c).
> And there is an apparent baud-rate mismatch and all the output is
> garbled now.  (with a scope I measured ~ 25.5 / 26 K, when I'm
> expecting 38.4k)
> 
> I think I'm missing something in the equation, but I'm not sure where
> it is.  If I simply update the CD to be 162 (162*38400*16 = 99,532,800
> ~ 100 MHz) the serial port is still dead.
> 
> Any ideas?

Hi Alan,

I suspect that your clock is really 66MHz (read it off the crystal, that 
is the definitive authority).  Generally BRGs don't lie - if your 
CONFIG_8260_CLKIN doesn't match the actual crystal, your baud rate is 
going to be wrong.  Your baud rate is right when CONFIG_8260_CLKIN is 
set to 66MHz and wrong when set to 100MHz - pretty strong evidence.

My theory is that your crystal is 66MHz but your CPU multiplier is 
misconfigured.  In the 8260 the CPU multiplier is selected by the HRCW 
(MODCK_H) _and_ some physical pins on the CPU (MODCK[1-3]) - your 8248 
may be different.

HTH,
gvb

[U-Boot-Users] BRGs on ep8248 after updating CLKIN

[Alan Bennett]

Ok, I don't know what I was thinking.  Yes, it's 66 MHz.

The only thing I can see is in the calculation for BUS_CLK
      speed.c   =   gd->bus_clk = clkin;

However, looking at the Ref Manual for the 8272, Figure 10-1,
   It shows a conflict:
        1. MAIN_PLL = 66MHz * (SCMR[pllmf]+1) = 66MHz*(5+1) = 396 MHz
        2. BUSCLK = MAIN_PLL/(SCMR[busdf]+1) = 396MHz /(3+1) = 99 MHz
        and then
        BUS_CLK = SCMR[corecnf] multiplier 1E=3.5*BUS_CLK

BUT CLKIN != BUS_CLK  (66MHz != 99MHz)

So could it be
		gd->cpu_clk = (gd->bus_clk * cp->b2c_mult) / 2;
instead of
		gd->cpu_clk = (clkin * cp->b2c_mult) / 2;

-Alan

On 11/29/07, Jerry Van Baren <gerald.vanbaren@ge.com> wrote:
> Alan Bennett wrote:
> > When I originally supported my ep8248-style board, I had
> > #define CONFIG_8260_CLKIN     66000000        /* in Hz */
> >
> > However, I noticed (after far too much time had passed) that my cpu
> > speed wasn't matching my expectations.  (reported 230 MHz, and
> > expected 350 MHz).
> >
> > This was rather easily fixed by changing the CONFIG_8260_CLKIN to 100 MHz:
> > #define CONFIG_8260_CLKIN     100000000       /* in Hz */
> >
> > However, my BRGs / SMC1 uart is now broke(baud-rate mismatch).  Does
> > anyone have experience with this section of u-boot that could help me
> > out?
> >
> > My BRG7 is configured by u-boot(1.3+) = 0x00010078 ~ CD = 60 (0x3c).
> > And there is an apparent baud-rate mismatch and all the output is
> > garbled now.  (with a scope I measured ~ 25.5 / 26 K, when I'm
> > expecting 38.4k)
> >
> > I think I'm missing something in the equation, but I'm not sure where
> > it is.  If I simply update the CD to be 162 (162*38400*16 = 99,532,800
> > ~ 100 MHz) the serial port is still dead.
> >
> > Any ideas?
>
> Hi Alan,
>
> I suspect that your clock is really 66MHz (read it off the crystal, that
> is the definitive authority).  Generally BRGs don't lie - if your
> CONFIG_8260_CLKIN doesn't match the actual crystal, your baud rate is
> going to be wrong.  Your baud rate is right when CONFIG_8260_CLKIN is
> set to 66MHz and wrong when set to 100MHz - pretty strong evidence.
>
> My theory is that your crystal is 66MHz but your CPU multiplier is
> misconfigured.  In the 8260 the CPU multiplier is selected by the HRCW
> (MODCK_H) _and_ some physical pins on the CPU (MODCK[1-3]) - your 8248
> may be different.
>
> HTH,
> gvb
>

[U-Boot-Users] BRGs on ep8248 after updating CLKIN

[Erik Christiansen]

On Thu, Nov 29, 2007 at 01:43:30PM -0700, Alan Bennett wrote:
> When I originally supported my ep8248-style board, I had
> #define CONFIG_8260_CLKIN	66000000	/* in Hz */
> 
> However, I noticed (after far too much time had passed) that my cpu
> speed wasn't matching my expectations.  (reported 230 MHz, and
> expected 350 MHz).
> 
> This was rather easily fixed by changing the CONFIG_8260_CLKIN to 100 MHz:
> #define CONFIG_8260_CLKIN	100000000	/* in Hz */
> 
> However, my BRGs / SMC1 uart is now broke(baud-rate mismatch).  Does
> anyone have experience with this section of u-boot that could help me
> out?

Only that U-Boot built and ran fine for me on an ep8248 board, without
any need to change the default CONFIG_8260_CLKIN.

If the "ep8248-style board" were mine, I'd physically compare the
crystal frequency with a real ep8248, before adjusting
CONFIG_8260_CLKIN. (Assuming PLL config is unchanged.) 

What does a frequency meter or CRO show on core_clk_out, during
core_hreset, on yours? Incidentally, mine also reports:

CPU:   MPC8248 (HiP7 Rev 14, Mask 1.0 1K50M) at 231 MHz
Board: EP8248E 1.0 CPLD revision 2

> My BRG7 is configured by u-boot(1.3+) = 0x00010078 ~ CD = 60 (0x3c).
> And there is an apparent baud-rate mismatch and all the output is
> garbled now.  (with a scope I measured ~ 25.5 / 26 K, when I'm
> expecting 38.4k)
> 
> I think I'm missing something in the equation, but I'm not sure where
> it is.  If I simply update the CD to be 162 (162*38400*16 = 99,532,800
> ~ 100 MHz) the serial port is still dead.
> 
> Any ideas?

From way over here, it looks a bit like an incorrect assumption. But
that's based on my tentative understanding that 350 MHz is "expected",
but 230 MHz works. (Serial was OK in that case.)

What is it that doesn't work with the default CONFIG_8260_CLKIN?
(And if it's only low CPU speed, then a higher crystal frequency or
lower PLL divider will be of more benefit?)

Regards,
Erik

[U-Boot-Users] BRGs on ep8248 after updating CLKIN

[Alan Bennett]

The main reason I began looking down this path was that within my
linux drivers, things were quite strange.  I'd do a schedule_timeout
for HZ/10 and with the help of a few test points and a logic analyzer,
I'd sleep a lot less than 1/10 of a second!  Often times I'd be out of
the loop in 60-80 msecs.  The only thing I could figure out was that
there was a miscalculation of the clocks by "something".
/proc/cpuinfo and other methods, u-boot included, seemed to think I
was running at 231 MHz, but empirical data showed that I was running
faster than that.  I also remembered that a while back, when we were
on the reference board (with the same clock configuration) we were
seeing ~350MHz.

Flawed, though it may have been, I began blaming many parts of the
system without understanding them, as you've read in my email.
However, I'm now wondering if the following interpretation is is
acceptable.  From what I read in the reference manual, the bus_clock
and clk_in are not "required" to be the same. Though several
references in the manual and in u-boot hard wire them to each other.

Looking at the Ref Manual for the 8272, Figure 10-1,
  It shows a conflict:
       1. MAIN_PLL = 66MHz * (SCMR[pllmf]+1)
               my board this is = 66MHz*(5+1) = 396 MHz
       2. BUSCLK = MAIN_PLL/(SCMR[busdf]+1)
               my board this is = 396MHz /(3+1) = 99 MHz
       3. CPU_CLK = SCMR[corecnf] multiplier 1E * BUS_CLK
               My board this is =3.5*99MHz = 346.5 MHz

BUT CLKIN != BUS_CLK  (66MHz != 99MHz) and (231MHz != 346.5MHz)

So the only way we can handle both the HIGH and LOW configuration
case, within speed.c is by calculating bus_clk according to the
reference manual and not hardcoding it to clkin.
i.e.
  gd->bus_clk = vco_out / (SCMR[busdf]+1)
and
  gd->cpu_clk = (gd->bus_clk * cp->b2c_mult) / 2

At least this is what I believe now.  Note: My serial port is much
happier and a 1/10 of a second timeout takes 1/10th of a second!

-Alan

On 11/29/07, Erik Christiansen <erik@dd.nec.com.au> wrote:
> On Thu, Nov 29, 2007 at 01:43:30PM -0700, Alan Bennett wrote:
> > When I originally supported my ep8248-style board, I had
> > #define CONFIG_8260_CLKIN     66000000        /* in Hz */
> >
> > However, I noticed (after far too much time had passed) that my cpu
> > speed wasn't matching my expectations.  (reported 230 MHz, and
> > expected 350 MHz).
> >
> > This was rather easily fixed by changing the CONFIG_8260_CLKIN to 100 MHz:
> > #define CONFIG_8260_CLKIN     100000000       /* in Hz */
> >
> > However, my BRGs / SMC1 uart is now broke(baud-rate mismatch).  Does
> > anyone have experience with this section of u-boot that could help me
> > out?
>
> Only that U-Boot built and ran fine for me on an ep8248 board, without
> any need to change the default CONFIG_8260_CLKIN.
>
> If the "ep8248-style board" were mine, I'd physically compare the
> crystal frequency with a real ep8248, before adjusting
> CONFIG_8260_CLKIN. (Assuming PLL config is unchanged.)
>
> What does a frequency meter or CRO show on core_clk_out, during
> core_hreset, on yours? Incidentally, mine also reports:
>
> CPU:   MPC8248 (HiP7 Rev 14, Mask 1.0 1K50M) at 231 MHz
> Board: EP8248E 1.0 CPLD revision 2
>
> > My BRG7 is configured by u-boot(1.3+) = 0x00010078 ~ CD = 60 (0x3c).
> > And there is an apparent baud-rate mismatch and all the output is
> > garbled now.  (with a scope I measured ~ 25.5 / 26 K, when I'm
> > expecting 38.4k)
> >
> > I think I'm missing something in the equation, but I'm not sure where
> > it is.  If I simply update the CD to be 162 (162*38400*16 = 99,532,800
> > ~ 100 MHz) the serial port is still dead.
> >
> > Any ideas?
>
> From way over here, it looks a bit like an incorrect assumption. But
> that's based on my tentative understanding that 350 MHz is "expected",
> but 230 MHz works. (Serial was OK in that case.)
>
> What is it that doesn't work with the default CONFIG_8260_CLKIN?
> (And if it's only low CPU speed, then a higher crystal frequency or
> lower PLL divider will be of more benefit?)
>
> Regards,
> Erik
>
>

[U-Boot-Users] BRGs on ep8248 after updating CLKIN

[Laurent Pinchart]

On Thursday 29 November 2007 23:39, Alan Bennett wrote:
> Ok, I don't know what I was thinking.  Yes, it's 66 MHz.
>
> The only thing I can see is in the calculation for BUS_CLK
>       speed.c   =   gd->bus_clk = clkin;
>
> However, looking at the Ref Manual for the 8272, Figure 10-1,
>    It shows a conflict:
>         1. MAIN_PLL = 66MHz * (SCMR[pllmf]+1) = 66MHz*(5+1) = 396 MHz
>         2. BUSCLK = MAIN_PLL/(SCMR[busdf]+1) = 396MHz /(3+1) = 99 MHz
>         and then
>         BUS_CLK = SCMR[corecnf] multiplier 1E=3.5*BUS_CLK
>
> BUT CLKIN != BUS_CLK  (66MHz != 99MHz)
>
> So could it be
> 		gd->cpu_clk = (gd->bus_clk * cp->b2c_mult) / 2;
> instead of
> 		gd->cpu_clk = (clkin * cp->b2c_mult) / 2;
>
> -Alan
>
> On 11/29/07, Jerry Van Baren <gerald.vanbaren@ge.com> wrote:
> > Alan Bennett wrote:
> > > When I originally supported my ep8248-style board, I had
> > > #define CONFIG_8260_CLKIN     66000000        /* in Hz */

If I'm not mistaken, your 66 MHz oscillator runs at 200/3 MHz, so 
CONFIG_8260_CLKIN should be set to 66666666.

> > > However, I noticed (after far too much time had passed) that my cpu
> > > speed wasn't matching my expectations.  (reported 230 MHz, and
> > > expected 350 MHz).
> > >
> > > This was rather easily fixed by changing the CONFIG_8260_CLKIN to 100
> > > MHz: #define CONFIG_8260_CLKIN     100000000       /* in Hz */
> > >
> > > However, my BRGs / SMC1 uart is now broke(baud-rate mismatch).  Does
> > > anyone have experience with this section of u-boot that could help me
> > > out?
> > >
> > > My BRG7 is configured by u-boot(1.3+) = 0x00010078 ~ CD = 60 (0x3c).
> > > And there is an apparent baud-rate mismatch and all the output is
> > > garbled now.  (with a scope I measured ~ 25.5 / 26 K, when I'm
> > > expecting 38.4k)
> > >
> > > I think I'm missing something in the equation, but I'm not sure where
> > > it is.  If I simply update the CD to be 162 (162*38400*16 = 99,532,800
> > > ~ 100 MHz) the serial port is still dead.
> > >
> > > Any ideas?
> >
> > Hi Alan,
> >
> > I suspect that your clock is really 66MHz (read it off the crystal, that
> > is the definitive authority).  Generally BRGs don't lie - if your
> > CONFIG_8260_CLKIN doesn't match the actual crystal, your baud rate is
> > going to be wrong.  Your baud rate is right when CONFIG_8260_CLKIN is
> > set to 66MHz and wrong when set to 100MHz - pretty strong evidence.
> >
> > My theory is that your crystal is 66MHz but your CPU multiplier is
> > misconfigured.  In the 8260 the CPU multiplier is selected by the HRCW
> > (MODCK_H) _and_ some physical pins on the CPU (MODCK[1-3]) - your 8248
> > may be different.

Best regards,

-- 
Laurent Pinchart
CSE Semaphore Belgium

Chauss?e de Bruxelles, 732A
B-1410 Waterloo
Belgium

T +32 (2) 387 42 59
F +32 (2) 387 42 75
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[U-Boot-Users] BRGs on ep8248 after updating CLKIN

[Alan Bennett]

Yes.  Thank you

On 11/30/07, Laurent Pinchart <laurentp@cse-semaphore.com> wrote:
> On Thursday 29 November 2007 23:39, Alan Bennett wrote:
> > Ok, I don't know what I was thinking.  Yes, it's 66 MHz.
> >
> > The only thing I can see is in the calculation for BUS_CLK
> >       speed.c   =   gd->bus_clk = clkin;
> >
> > However, looking at the Ref Manual for the 8272, Figure 10-1,
> >    It shows a conflict:
> >         1. MAIN_PLL = 66MHz * (SCMR[pllmf]+1) = 66MHz*(5+1) = 396 MHz
> >         2. BUSCLK = MAIN_PLL/(SCMR[busdf]+1) = 396MHz /(3+1) = 99 MHz
> >         and then
> >         BUS_CLK = SCMR[corecnf] multiplier 1E=3.5*BUS_CLK
> >
> > BUT CLKIN != BUS_CLK  (66MHz != 99MHz)
> >
> > So could it be
> >               gd->cpu_clk = (gd->bus_clk * cp->b2c_mult) / 2;
> > instead of
> >               gd->cpu_clk = (clkin * cp->b2c_mult) / 2;
> >
> > -Alan
> >
> > On 11/29/07, Jerry Van Baren <gerald.vanbaren@ge.com> wrote:
> > > Alan Bennett wrote:
> > > > When I originally supported my ep8248-style board, I had
> > > > #define CONFIG_8260_CLKIN     66000000        /* in Hz */
>
> If I'm not mistaken, your 66 MHz oscillator runs at 200/3 MHz, so
> CONFIG_8260_CLKIN should be set to 66666666.
>
> > > > However, I noticed (after far too much time had passed) that my cpu
> > > > speed wasn't matching my expectations.  (reported 230 MHz, and
> > > > expected 350 MHz).
> > > >
> > > > This was rather easily fixed by changing the CONFIG_8260_CLKIN to 100
> > > > MHz: #define CONFIG_8260_CLKIN     100000000       /* in Hz */
> > > >
> > > > However, my BRGs / SMC1 uart is now broke(baud-rate mismatch).  Does
> > > > anyone have experience with this section of u-boot that could help me
> > > > out?
> > > >
> > > > My BRG7 is configured by u-boot(1.3+) = 0x00010078 ~ CD = 60 (0x3c).
> > > > And there is an apparent baud-rate mismatch and all the output is
> > > > garbled now.  (with a scope I measured ~ 25.5 / 26 K, when I'm
> > > > expecting 38.4k)
> > > >
> > > > I think I'm missing something in the equation, but I'm not sure where
> > > > it is.  If I simply update the CD to be 162 (162*38400*16 = 99,532,800
> > > > ~ 100 MHz) the serial port is still dead.
> > > >
> > > > Any ideas?
> > >
> > > Hi Alan,
> > >
> > > I suspect that your clock is really 66MHz (read it off the crystal, that
> > > is the definitive authority).  Generally BRGs don't lie - if your
> > > CONFIG_8260_CLKIN doesn't match the actual crystal, your baud rate is
> > > going to be wrong.  Your baud rate is right when CONFIG_8260_CLKIN is
> > > set to 66MHz and wrong when set to 100MHz - pretty strong evidence.
> > >
> > > My theory is that your crystal is 66MHz but your CPU multiplier is
> > > misconfigured.  In the 8260 the CPU multiplier is selected by the HRCW
> > > (MODCK_H) _and_ some physical pins on the CPU (MODCK[1-3]) - your 8248
> > > may be different.
>
> Best regards,
>
> --
> Laurent Pinchart
> CSE Semaphore Belgium
>
> Chauss?e de Bruxelles, 732A
> B-1410 Waterloo
> Belgium
>
> T +32 (2) 387 42 59
> F +32 (2) 387 42 75
>
>